1. Field of the Invention
The present invention relates to a method of cutting pieces of an extruded substance and depositing such pieces on separate wrapping sheets.
2. The Prior Art
In certain prior art methods of the above mentioned-type the pieces are removed as they are cut from the extruded string of substance and conveyed by means of separate displacement devices or the like to be deposited on separate wrapping sheets. The result of such handling of the pieces is that the string of substance cannot be extruded continuously.
Another prior art method is disclosed in U.S. Pat. No. 4,094,122 according to which the cut pieces of substances continously are deposited directly onto separate wrapping sheets, so that the transfer operations and displacement devices required for such transfer are avoided. This is achieved by placing the leading end of the substance being extruded directly onto the wrapping sheet conveyed by the conveyors a sufficient distance from the leading edge of the wrapping sheet to allow the protruding leading edge of the sheet to form a front end closure of the finished package, advancing the trailing edge of the wrapping sheet and the leading edge of a succeeding wrapping sheet in a manner so that they form a mutual overlap of a size which is at least sufficient to form a rear end and a front end closure in the respective finished pre-packages, and then by accelerating the leading wrapping sheet together with the cut piece of substance thereon in relation to the extruding velocity of the substance.
As a result, it is possible to extrude the substance and convey the sheets continuously, as the cut surfaces formed by cutting the individual pieces of substance are moved away from each other. Thus, the leading ends and the succeeding trailing ends of the wrapping sheets are kept clear of extruded substance and the sheets, each having a piece of substances deposited thereon, are conveyed to a subsequent mechanism for wrapping the single sheet around the pertaining piece of substances and for folding the front and rear end closures. Moreover, the substance is handled gently as the pieces need no further handling when deposited onto the sheets.
However, as far as production is concerned, the invention according to U.S. Pat. No. 4,094,122 suffers from certain restrictive drawbacks. Thus, the extruded pieces of substances are cut on the basis of a flow measurement, i.e. a measurement of volume, performed within the extruder proper before the product leaves the extruder, which naturally results in a certain inaccuracy in the size of the measured pieces of substances, because the measuring signal controlling the cutter allows movements in the extruded mass between the point of measurement and the point of cutting which is located a certain distance outside the mouth of the extruder. Furthermore, the cut is performed against a solid base on the conveyor belt at a time when the extruded substance is placed upon the overlap of two consecutive wrapping sheets. As the wrapping sheet with the cut piece of substance thereon has to be accelerated immediately after the cut has been made to separate it from the succeeding underlapping sheet, the invention according to U.S. Pat. No. 4,094,122 has clear physical limits as to how much a piece of substance may weigh in order to make it possible to accelerate and separate the two sheets in question, as blocks of extruded substance may cause such friction between the overlapping wrapping sheets due to the weight proper of the substance that in practice the machine cannot produce the acceleration pull required to separate the sheets. Indeed, it also appears clearly from U.S. Pat. No. 4,090,122 that the invention particularly concerns cutting, conveying and wrapping extruded pieces of substances of a very small height with an equal small weight, so that the above-mentioned drawbacks will have relatively little significance.